Peristalic pump having hinged backing plate

ABSTRACT

A peristaltic hose pump comprising a roller wheel, which can rotate about a roller wheel axis and which has rollers that are mounted on the roller wheel. The rollers roll along a circular path having a certain radius with respect to the roller wheel axis. The peristaltic hose pump also comprises a pressure arched element with a supporting surface, whereby the supporting surface extends along a circular path having a certain radius around the rotation axis of the roller wheel. In addition, a flexible hose can be inserted between the supporting surface and the rollers of the roller wheel.

SCOPE OF THE INVENTION

The invention relates to a peristaltic hose pump comprising a rollerwheel, which can rotate about a roller wheel axis and which has rollersthat are mounted on the roller wheel. The rollers roll along a circularpath having a certain radius with respect to the roller wheel axis. Theperistaltic hose pump also comprises a pressure arched element with asupporting surface, whereby the supporting surface extends along acircular path having a certain radius around the rotation axis of theroller wheel. In addition, a flexible hose can be inserted between thesupporting surface and the rollers of the roller wheel.

STATE OF THE ART

A peristaltic hose pump of the aforementioned design is known from DE-G83 29 579. Here the pressure arched element is formed by a deformableband, the one end of which is firmly clamped, while its other end isadjustably held in its axial direction, which facilitates the adaptationto different hose diameters. The band made of a metallic material,plastic or fabric has the disadvantage of too high elasticity.Furthermore, the elastic band is stretched over the rollers andrespectively runs in a straight fashion between the rollers, so that theliquid swept volume formed within the hose is reduced, so that thevolume transported and thus the delivery rate are relatively low.

In order to achieve high pressures and delivery rates with peristaltichose pumps and to obtain an exact pinching of the hose between therollers of the roller wheel and the pressure arched element, aperistaltic hose pump incorporating a rigid pressure arched element isknown from practice. Here precision hoses with small tolerances areused, and the mechanical parts are manufactured and mounted with highprecision. In spite of this, faults occur due to hose tolerances as wellas manufacturing and mounting tolerances in the mechanical parts.Because tolerances cannot be completely excluded, they are compensatedby means of a spring with which the rigid pressure arched element ispressed against the roller wheel, an arrangement which can, for example,be found on arthroscopic pumps made by the firms Stryker, Arthrex andEMS. The disadvantage here is that the spring force is directional andonly provides the hose with a precise impression at that point of theroller that is in the line of the force. At all other points of theroller only a component of the spring force is exerted. Where the forceacts 90° to the roller, this component is equal to zero. This leads toan only limited compensation for tolerance. It is not possible togenerate high pressures for high delivery rates.

TECHNICAL OBJECTS OF THE INVENTION

The technical object of the invention is thus to provide a peristalticpump that has an improved delivery pressure and, in particular, thatthus also provides an improved delivery rate.

BASIS OF THE INVENTION AND PREFERRED EMBODIMENTS

To solve this problem, the invention provides that the supportingsurface is made of an elastically deformable synthetic material, and thepressure arched element is pre-shaped with the provision that theextension of the supporting surface, when the pressure arched element isnot under tension, essentially corresponds to the extension of thesupporting surface when under tension. This ensures that the hose isclasped between the roller and the pressure arched element by the samecontinuous amount in each position of the roller with respect to thepressure arched element. During the circulating movement of the rollerwheel, the elastic deformation (prestress) runs with the roller throughthe pressure arched element, so that the clasping force always actsperpendicular to the roller. This facilitates compensation for greatertolerances in the hose, production and assembly, which results inconsiderable cost savings in manufacturing the hose pump. Depending onthe respective design of the elastically deformable supporting surfaceof the pressure arched element, the pressures and delivery rate can beincreased by at least 50% as compared with a rigid pressure archedelement. Delivery rates of more than 2 l/min up to 3 l/min can beaccomplished. The unstressed condition corresponds to a mountingposition of the pressure arched element in which a hose can be inserted.The stressed condition corresponds to an operating position in which thesupporting surface is moved in directions towards the rotation axis ofthe roller wheel relative to the mounting position, whereby the hose isclasped between the roller rollers and the supporting surface. Thepressure arched element is mounted or fixed in the region of its twoends, but other than that it is free, i.e. it is not supported by anyother components.

In the state of the art according to DE-G 83 29 579, the elastic band istensioned over the rollers and runs straight between the rollers, sothat the liquid delivery volume within the flexible hose is reduced, sothat the volume transported and thus the delivery rate are relativelysmall. On the other hand, the rigid pressure arched element, which ispressed against the roller wheel by spring action, only presses the hoseexactly in the direction of force of the spring in the roller position,so that no high pressures for a high delivery rate are generated. Incontrast, the hose pump according to the invention provides that thereis sufficient space between two rollers, respectively to transport theliquid, while at the same time high pressures and high delivery ratescan be accomplished. The invention thus overcomes the disadvantagesinherent in the previously known hose pumps.

In one embodiment the pressure arched element consists of a rigidmetallic material and is provided with the supporting surface made ofthe elastically deformable synthetic material. In a further embodimentthe pressure arched element is wholly made of the elastically deformablesynthetic material. The synthetic material is preferably whitepolyoxymethylene (POM). The pressure arched element is thereby made ofmaterials having high elasticity, and can be engineered in such a waythat when it closes due to a prestressed inherent deformation, itpinches the hose on the rollers. When the roller wheel moves, theelastic deformation (prestress) runs through the pressure arched elementwith the roller.

Further advantageous embodiments of the invention are shown in thefurther subclaims. Reference is hereby particularly made to thetensioning device according to subclaim 8. This device tensions thepressure arched element at the same time that the hose pump is closed,so that the operator is not at risk to get his fingers caught betweenthe rollers and the pressure arched element in its stressed condition.

EXAMPLES OF EMBODIMENTS

The following examples serve to further explain the invention with thehelp of the figures shown. The figures represent the following:

FIG. 1: perspective representation of the front plate of the devicehousing for two peristaltic hose pumps, without inserted flexible hoses,whereby the left hose pump is open and the right hose pump is closed;

FIG. 2: perspective representation of the front plate according to FIG.1, without the covers for the two hose pumps;

FIG. 3: top view of the representation shown in FIG. 2, with an insertedhose;

FIG. 4: perspective front view of the pressure arched element of a hosepump, and

FIG. 5: perspective rear view on to the pressure arched element withclamping disk.

FIGS. 1 through 3 show the front plate 15 of a device housing for twoperistaltic hose pumps 20, 21, whose roller wheels 1 are each equippedwith four rollers 2 and are driven by electric motors 16 mounted on therear side of the front plate 15. Assigned to each roller wheel 1 withfour rollers 2 there is a pressure arched element 3 with a supportingsurface 4 on the side facing the rollers 2, whereby the supportingsurface 4 is provided with a run-in zone 5, a middle zone 6 and arun-out zone 7, as detailed in FIG. 4. The pressure arched element 3 ispivotally mounted on a pivot axis 8 arranged on the front plate 15,while on its opposite end it is provided with a dowel pin 10 which onthe one hand engages in an adjusting link 25 and, on the other hand,acts in combination with the snatch posts 26, 27 of a clamping disk 24,that is rigidly mounted on the front plate 15. Firmly attached to theadjusting link 25 is a closing plate 13, which can be pivoted by meansof an actuating element 11 that is attached to it.

The rollers 2 of the peristaltic hose pumps 20, 21 roll along a circularpath having a radius R1 with respect to the rotation axis D of theroller wheel 1 along the supporting surface 4 of the pressure archedelement 3, whereby the supporting surface 4 extends along a circularpath having a radius R2 around the rotation axis D of the roller wheel1, and whereby a flexible hose 19 can be inserted between the supportingsurface 4 and the rollers 2 of the roller wheel 1. In the embodimentshown, the pressure arched element 3 and the supporting surface 4 aremade in one piece and of an elastically deformable synthetic material.In another embodiment not shown here, the pressure arched element 3 canalso be made of a metallic material and be provided with an inner-lyinglining made of synthetic material, which then forms the supportingsurface 4. The pressure arched element 3 is preshaped with the provisionthat the extension of the supporting surface 4 when not under tensionessentially corresponds to the extension of the supporting surface 4when under tension.

The preferred synthetic material used is polyoxymethylene (POM).Preferably Delrin, manufactured by Dupont, or Hostaform, manufactured byHoechst are used. The preferred modulus of elasticity in tension is≧3000 MPa (megapascal). The bending fatigue strength is preferably ≧30MPa. The impact strength at a room temperature of 23° C. is preferably≧130 KJ/m² (kilojoules per square meter). The coefficient of slidingfriction against steel for a dry run is preferably ≧0.30. In tests thatwere conducted, a POM synthetic material with these characteristicsproved particularly suitable for the supporting surface 4 of thepressure arched element 3 of the hose pumps 20, 21.

Opposing the pressure arched element 4 of each hose pump 20, 21 is abracket 17 firmly mounted on the front plate 15 and having two passageopenings 18 to insert a flexible hose 19 that is respectively arrangedtangentially to the roller wheel 1 and comes to rest on the supportingsurface 4 on the inner side of the pressure arched element 3.

The pressure arched element 4 is provided with a run-in zone 5, a middlezone 6 and a run-out zone 7, whereby the pressure arched element 3has—at least in the run-out zone 7, and preferably also in the run-inzone 5—a larger cross section as compared with the middle zone 6,preferably an increased thickness in directions orthogonal to thesupporting surface. With respect tote rotation axis D of roller wheel 1,the middlezone 6 extends across an angle of 10 to 90°, preferably 20 to60°, with respect to the embracing of the roller wheel 1 by the hose 19.With respect to the rotation axis D, the pressure arched element 3extends across an angle of 90 to 180°, preferably 120 to 170″.

The pressure arched element 3, which is rigidly arranged on the frontplate 15 and mounted on the pivot axis 8 parallel to the rotation axis Dof the roller wheel 1, is, at its other end, pivotally mounted between amounting point I for the hose 19 and an operating point II for the hoseby means of a fixation device 9. For this purpose, the fixation device 9comprises a dowel pin 10 located at the second end of pressure archedelement 3, as well as a closing plate 13 with an actuating element 11,which is rotatably mounted around a tension rotation axis S runningparallel to the rotation axis D of the roller wheel 1. When swinging theclosing plate 13 over from the mounting position I of the hose 19 (inFIG. 1, left hose pump 20) into the operating position II (in FIG. 1,right hose pump 21), the dowel pin 10 is moved from the one snatch post26 of the clamping disk 24 to its other snatch post 27, whereby theclamping disk 24 is embodied in a springy manner by an arc-shaped slit28 running between the two snatch posts 26, 27. In the operatingcondition II, the closing plate 13 facially covers the roller wheel 1 aswell as the inserted hose 19, and thus fixes the hose 19 in thedirection of the rotation axis D of the roller wheel 1. In the operatingcondition II, the closing plate 13 can be positively engaged in place.The roller wheel 1 and/or the pressure arched element 3 areinterchangeable.

In FIG. 1, radius R1 to the hose pump 20 is defined as the rollingradius of the outside of each roller 2 with respect to the rotation axisD of the roller wheel 1, and radius R2 is defined as the distancebetween the supporting surface 4 from the middle axis D of the rollerwheel 1. With respect to their radial difference R2−R1, the roller wheel1 and/or the pressure arched element 3 can be selected with thestipulation that a prescribed hose with a wall thickness of <R2−R1/2 isusable.

The peristaltic hose pumps 20, 21 shown, form an arthroscopic pump inwhich the hose pump 20 shown on the left in FIG. 1 forms the suctionside, and the hose pump 21 shown on the right in FIG. 1 forms theflushing side. The hose pump 20 on the suction side rotates clockwisewhile the hose pump 21 on the flushing side rotates counter clockwise.Mounts 22 for the hose 19 are provided for both hose pumps 20, 21. Themounts 22 incorporate pressure sensors. Between both hose pumps 20, 21,the front plate 15 has a window 23 for a display showing the values forpressure, delivery rate and similar functions of the arthroscopic pump.

In an alternative embodiment the pressure arched element 3 has, at leastin the middle zone 6, a slit-formed recess that extends along a circularpath around the rotation axis D of the roller wheel 1.

1. A peristaltic hose pump comprising: a roller wheel which can rotate about a roller wheel axis D and which has rollers that are mounted on said roller wheel, wherein said rollers roll along a circular path having a radius R1 with respect to said roller wheel axis D; a pressure arched element with a supporting surface, wherein said supporting surface extends along a circular path defining an extension having a radius R2 around said rotation axis D of said roller wheel; a flexible hose inserted between said supporting surface and said rollers of said roller wheel, said supporting surface being made of an elastically deformable synthetic material, said pressure arched element being pre-shaped such that said extension of said supporting surface, when said pressure arched element is not under tension, essentially corresponds to said extension of said supporting surface when under tension, wherein a fixation device comprises a dowel pin located at an end of said pressure arched element and a closing plate, said closing plate being rotatably mounted around a tension rotation axis running parallel to said rotation axis D of said roller wheel, whereby said closing plate interacts with said dowel pin such that said dowel pin leaves a first snatch post and is pressed into a second snatch post of a clamping disk when said closing plate is turned from a hose mounting position to an operating position.
 2. A peristaltic hose pump according to claim 1, wherein said synthetic material is polyoxymethylene (POM).
 3. A peristaltic hose pump according to claim 1, wherein said synthetic material has a modulus of elasticity in tension of ≧1000 MPa (megapascal), a bending fatigue strength of ≧10 MPa, and an impact strength at a room temperature of 23° C. of ≧70 KJ/m² (kilojoules per square meter).
 4. A peristaltic hose pump according to claim 3, wherein said synthetic material has a modulus of elasticity in tension of ≧3000 MPa (megapascal), a bending fatigue strength of ≧30 MPa, and an impact strength at a room temperature of 23° C. of ≧130 KJ/m² (kilojoules per square meter).
 5. A peristaltic hose pump according to claim 1, wherein said pressure arched element has a run-in zone, a middle zone and a run-out zone, whereby at least said run-out zone has a larger cross section as compared with said middle zone.
 6. A peristaltic hose pump according to claim 5, wherein said run-in zone also has a larger cross section as compared with said middle zone, an increased thickness in directions orthogonal to said supporting surface.
 7. A peristaltic hose pump according to claim 1, wherein a middle zone extends across an angle of 10° to 90° an embracing of said roller wheel by said hose and with respect to said roller wheel axis D, said pressure-arched element extends across an angle of 90° to 180°.
 8. A peristaltic hose pump according to claim 1, wherein, with respect to said rotation axis D, said pressure arched element extends across an angle of 90° to 180°.
 9. A peristaltic hose pump according to claim 1, wherein said pressure arched element is at its first end mounted on a pivot axis rigidly arranged on a hose pump and running parallel to said rotation axis D of said roller wheel, and at its second end by a pivoting means of a fixation device so that it can pivot between a hose mounting point and an operating point.
 10. A peristaltic hose pump according to claim 1, wherein, in an operating position, a closing plate facially covers said roller wheel as well as said hose placed around it, in such a way that said hose is fixed in the direction of said rotation axis D of said roller wheel.
 11. A peristaltic hose pump according to claim 1, wherein, in an operating position, a closing plate is positively engaged in place.
 12. A peristaltic hose pump according to claim 1, wherein said roller wheel and said pressure arched element are replaceable.
 13. A peristaltic hose pump according to claim 1, wherein, with respect to their radial difference R2−R1, said roller wheel and said pressure arched element can be selected with the stipulation that in mounting position a prescribed hose with an outer diameter of less than R2−R1 can be inserted.
 14. A peristaltic hose pump according to claim 1, wherein, with respect to their radial difference R2−R1, said roller wheel and said pressure arched element can be selected with the stipulation that a prescribed hose with a wall thickness of <(R2−R1)/2 can be inserted.
 15. A peristaltic hose pump comprising: a roller wheel rotating about a roller wheel axis D and having rollers mounted on said roller wheel, wherein said rollers roll along a circular path having a radius R1 with respect to said roller wheel axis D; a pressure arched element with a supporting surface, whereby said supporting surface extends along a circular path having a radius R2 with respect to said roller wheel axis D; and a closing plate rotatably mounted around a tension rotation axis S running parallel to said roller wheel axis D and having a mounting position and an operating position, wherein a flexible hose is inserted between said supporting surface and said rollers, wherein said supporting surface is made of an elastically deformable synthetic material, and said pressure arched element is pre-shaped with the provision that an extension of said supporting surface, when said pressure arched element is not under tension, essentially corresponds to said extension of said supporting surface when under tension.
 16. A peristaltic hose pump comprising: a selective pressure inducing guide for a flexible hose defined by an inner guide means including a roller wheel with a circular perimeter rotating about an axis D having a plurality of rollers, each of said rollers mounted near the outer edge of said circular perimeter to rotate about its own axis, said plurality of rollers combining to form an inner circular path with an annular radius R1 with respect to said axis D for said flexible hose; an outer guide means including a pre-shaped pressure arched element with a flexible supporting surface extending to form an outer circular path with an annular radius R2 with respect to said axis D for said flexible hose; and a closing plate rotatably mounted around a tension rotation axis S running parallel to said roller wheel axis D and having a mounting position and an operating position, wherein said closing plate includes an actuating means which can be actuated to close said closing plate by hand and said supporting surface, made of an elastically deformable synthetic material, retains its shape when tension is applied by said flexible hose inserted between said inner guide means and said outer guide means with said closing plate in said operating position. 